This is just sort of a half-baked idea. If it interests you enough, maybe we can flesh it out together.
It turns out that Satan is a woman. The whole cliche selling your soul for one or two wishes thing? The myth is based on reality. She comes to you, offering to give you two wishes, anything within her power (which is very extensive) will be yours... But you know how Satan always manipulates your words? Sort of like the movie Bedazzled. Brendan Fraser wants a big cock? Your wish is granted! Oh, but you're also gay. You want to be a famous athlete? Your wish is granted! Oh, but you're shrimpdicked. You want to be rich and powerful, and be married to a girl you adore? Your wish is granted! Too bad you're a Columbian druglord, and your wife hates your guts... You see how it works.
Except, Satan didn't do her research when she came to your doorstep. You're a lawyer; You know how to perfectly word binding contracts, and when you print up an x page contract for Satan to sign, promising your soul for the wish you've listed in fine print, she looks over it in confusion before she signs it too. Your wish is granted...!
That's the gist of my idea. I don't know what it would turn into, but I'm open to anything. If it hasn't been clarified, I'm looking to play Satan. I don't plan on being very biblical, as I have never read the bible. Post here or PM me if you're interested in collaborating.